在区间与区间之距——IR距概念的基础上给出了相应的可拓评价方法——区间可拓评价方法，并在区域水环境质量评价中给出实例。解决待评事物由实测数据的种种不确定性产生的区间数的评价问题。

On the basis of IR distance this paper gives out IR extension assessment method and its application to water environmental quality assessment. This method solves assessment problems while quantity of assessed matter-element is an interval number produced by a variety of uncertainty.